Same question please advise!
Trying to use Xfinity bill as a proof of address, but billing address still reflects old location
If you moved and transferred your service, you have a new account number, and that is the account you should be signing in to. Accounts are tied not only to an account holder, but also to an address.
@Dzermani wrote: ... billing address still reflects old location
Double check your UserIDs on your home system with the Lookup tool at https://idm.xfinity.com/myaccount/lookup. After you enter the requested information you'll see a list of the UserIDs on your account. When you move Comcast doesn't always transfer your logins/email addresses from the old account to the new one.
If you still don't have access to the new account, contact one of their reps at the phone number on your bill or 1-800-Comcast, or use one of the other options on https://www.xfinity.com/support/contact-us/ and have them fix the problem.